Catalyst regeneration



. l C ORIGINAL COMBUSTION June 20, 1939. P, E, i UHL 2,1 2,893-

- CNI'ALYST REGENERATION Filed Sept. 1, 1938 0/1. OUTLET EXHAUST o/z. nvus-r FR M pREI-IEATEZ Patented June 20, 1 939 I g fumreo STATES PATEN ornce Application September. 1, 1938, Serial No. 227,897

1 Claims. (01.. 23-238) This invention relates to improvements in the peratures are produced. Furthermore, the unreregeneration of catalysts; morevparticularly it generated catalyst is preheated bycombustion relates to the regeneration of the catalysts of the Y gases moving in advance of the flame front, andcontact type, such for example, as are used in hence the unregenerated catalytic mass also atthe conversion of relatively heavy hydrocarbon tainsa progressively higher temperature. The oils into fractions boiling within the gasoline passage of hot products of combustion over the range. unregenerated catalyst in advance of the flame In using an adsorptive catalytic substance, front causes a baking of the tarry or cokey masuch as an acid treated'clay or a synthetic cataterial so that it is diflic'ult to burn and remove p lyst of the contact type in the cracking of hydrothe same. i 10 carbons, the catalyst loses efiiciency due to the In order to overcome the disadvantages of the deposition of carbonaceous or tarry material former process of regenerating a contact catalyst upon it'and this unavoidably occurs, even where by the combustion method, I propose to regenthe most careful precautions are taken in macrate the catalyst by so manipulating the com- 5 nipulating the process. When the accumulation bustionjprocess that the flame front or active.

of said carbonaceous or tarry materials amounts combustion zone moves or is propagated in a dito about say 2% to 5%, based on the weight of rection opposite the flow of oxygen-containing gas the catalyst, the efl'iciency of the catalyst is masupporting the said combustion. In carrying the terially' reduced. Numerous proposals have been invention into effect, I first cause ignition of the made for regenerating catalysts including treattarry material deposited on the catalyst at one I ment of the said catalyst with various solvents and of the reaction chamber or reactor, and then and also combustion of the tarry material or coke introduce an oxygen-containing gas at the other in the piksence of an oxygen-containing gas. end of the chamber or portion 'at a temperature It is an object of my invention to regenerate a below that necessary to support combustion,

, spent catalyst by combustion of the tarry 'matewhereupon the gas passes through the catalyst r rial or coke deposited thereon, in a manner such which is hot and is thus raised to ignition temthat overheating, baking, or fusion and conseperatures at the time it reaches the flame front quent impairment of the catalyst is avoided. In or active combustion zone. The flame front regenerating a catalyst by combustion or burning under those conditions necessarily moves through of the tarry material from the catalyst, it is esthe catalyst in the opposite direction to the flow 30 sential that the catalyst, during combustion of of oxygen-containing gas, as will appear more the tar or other deposit, is not heated above a fully from the following description. certain maximum temperature, say 1100 F., Reference is now made to the accompanying since treating to higher temperatures may cause drawing in which the figure shows in elevation a sintering or fusion of. the catalyst and injury to catalytic oil cracking chamber with some accesr its structure. It is, of course, well known that sory apparatus, the reaction chamber proper bethe physical structure of acatalyst of the contact ing broken away in part to show the catalyst type plays a very important role in theefiiciency within and indicate a position of the flame front of the same in the catalytic reaction. or active combustion zone. It will be understood In the former processes of regeneration by the that, athough not thus fully illustrated, the re- 40 combustion method, air or air diluted with inert action chamber shown may be of any convengas, is introduced at an elevated temperature into tional shape and size and form part of a comthe reaction chamber containing the catalyst bi-nation of heaters, Vaporizers, fractionating colwhich is also at a high temperature. The tarry umns, condensers, receiver s, conduits and the 5 material under these conditions ignites at the like, employed in cracking processes. The flow point of entrance of the oxygen-containing gas of hydrocarbon oil, during cracking, through the and the flame front or active combustion zone reactor is indicated in the drawing, the oil from gradually Proceeds through the ll ass the preheaters entering through valved line 0 and until substantially all the tarry material has been exiting through valved line p.

a consumed. This method has e sa ag It will be assumed for purposes of illustration that after the flame has progressed part way that a catalytic cracking operation has beencomthrough the bed of catalyst, the catalyst which pleted and the valves in lines o andp closed. The has been regenerated serves to preheat the air catalyst which is at a temperature of say 820 F. passing through it toward the flame front and as contains about 0.6% to 5.0% carbonaceous mat- 65 a result progressively higher flame front tem-' ter. It is customary first-to purge the-catalyst,

following cracking, with an inert gas such as steam to remove highly volatile hydrocarbon constl'tuents and this may be accomplished byforcing steam through the valved line H into reactor L and withdrawing the steam and volatile material through valved line D. The temperature of the catalytic mass during purging is changed very little. 7

After purging of the catalyst, heated gas containing oxygen is admitted at the top of chamber L through H and ignition initiated in upper A zone, combustion gases passing downwardly and exhausting at the bottom through D.

Then the initial air supply through H is discontinued and air diluted with nitrogen or carbon dioxide or steam or some inert gas and below ignition temperature, say at 650F., is forced, for example pumped, into the bottom of the chamber L through C and proceeds upwardly in -a direction opposite to the direction of the downwardly moving flame which advances from zone A toward zone G The gaseous products of combustion exhaust through valved line K.

As indicated in the drawing then, A and G rep resent original combustion zones or flame fronts and' the regenerated catalyst in these regions -may be at a temperature of about 900-1000 F.

Also in the drawing the flame front is shown in zone B where a temperature of say 1100" F. prevails. Below the flame front in B in zone E, the

temperature may be between 925 and 1000 Fm Below E there is a lower region or zone F in which the temperature of the catalyst may be at about 800 to 925 F. The progress of the flame front or combustion zone through the catalyst can be observed by means of thermo-couples J. Thus in the drawing, the thermo-couples in the neighborhood of B would register, as previously stated, 1100 F. Above B, that is, in regenerated regions A and G, the entire body of catalyst is at a temperature of about 900-1000" F.

In order to give more details, it is pointed on that ordinary undiluted air containing about, 20% oxygen, admitted through H, may be used to initiate combustion at or above zone A and when it has advanced toward zone G the air supply through H is discontinued and thereafter oxygen-containing gas is supplied through (3. The oxygen content of the diluted air entering at C, after the supply through H is discontinued, may be as low as 1%. Furthermore, a back or outlet pressure, indicated by gauge 1, of about 5 to 105-; lbs/sq. in. in excess of atmospheric pressure with about 40 lbs/sq. in. preferred, may be maintained during regeneration in order to obtain best results. The velocity of the air stream entering through C may be such as to discharge about 3000 volumesof gas, measured at standard conditions, per volumeof catalyst per hour. The time required to regenerate a catalyst according to my improved method, is about from 10 to 50 minutes per 3 feet of catalyst bed length.

It is not to be understood that the zones A, B, 7

Thus, B has been called the flame front zone simply because the highest temperature prevails therewat the particular time when the process of regeneration had advanced to the point represented in the drawing. And the flame front is considered to be moving downwardly because the thermo-couples, beginning at the top, will indicate a maximum temperature region which moves downwardly during regeneration.

After the operating and purging Parts of a catalytic cracking cycle, and when about to introduce oxygen-containing gases for regeneration, another modification of my invention can be practiced as follows: Relatively cool oxygen-containing gas is introduced at a temperature below ignition temperature through 0. This gas will cool the spent catalyst at lower F region picking up heat as it passes upwardly through the catalyst. At some point, depending upon rate of flow, catalyst temperature, inlet gas temperature, oxygen concentration and similar variables, it will be sufliciently heated to cause combustion of'the tarry material or coke on the catalyst. It will then be further heated by heat of combustion, which will accelerate the rate of burning as itpasses through the catalyst. By proper adjustment of gas flow rate, temperature and oxygen concentratiomrapid combustion can be limited to a zone near the outlet (upper A) and can be caused to move toward the gas inlet C at the desired downwardly rate by appropriate control of the above variables, for example by increasing the temperature of the oxygen-containing gas at a predetermined rate.

wardly adsorbing heat from the hotter catalyst until finally it is sufficiently heated in the region at or above A to cause rapid combustion of the carbonaceous matter at A. Originally at B, E and F no, or merely incipient, combustion occurs. By thereafter gradually increasing the temperature of the oxygen-containing gas entering at C the said gas will arrive at a lower point sufii-ciently heated to cause rapid combustion. 'I'hisis to say, the distance from A zone to lower F zone gradually decreases as the zone of rapid combustion moves do wardly and the shortened time of contac of oxygen-containing gas with the catalyst for preheatingpurposes must be compensated for by gradually increasing the temperature of the incoming gas until finally it must be heated to say 8003 F. when the flame front has advanced into zone By operating in either above described method, it is possible to regenerate a catalyst without causing hot spots or local overheating or baking of tarry constituents into the catalytic mass, and consequent injury of the catalyst structure. That is to say, since the catalyst to be regenerated is not preheated by combustion gas in advance of the. flame front, prevailing temperatures in the active combustion zone or flame front will be merely that caused by straight combustion and will, not have an added heat content, due to heat absorption prior to combustion by the unregenerated catalyst from the hot gaseous products of combustion. A further advantage of my methods of regenerating a catalyst is that the same is kept at a uniform and homogeneous temperature following regeneration. Thus the temperature of the regenerated catalyst may be maintained substantially uniform through its en- *tire mass, which condition is of great aid in the tically cracking relatively heavy hydrocarbon oils, the present regenerating process is obviously applicable to the regeneration of contact catalyst broadly whether they be used invcracking, polymerizing, hydrogenation, oxidation or any other process where a combustible deposit is formed on the said catalyst, thus impairing its effectiveness. Consequently, the present process is applicable to the regeneration of clay,'silica and other gels, zeolite, pumice, activated alumina, activated carbon and similar adsorptive bodies employed as catalysts. Also. my improved regenerative process is applicable to catalysts whether they be in lump, granular, pellet, or powdered form.'

In the foregoing description, no emphasis was placed on any particular manner of-disposing the catalyst within the chamber but,- forbne reason or another, it may, in some process, be desirable to provide 9 to beds of catalyst in a singlechamber, in which event, the oxygencontaining gas supply lines and exhaust pipes may conveniently be arranged in a manner taught by the present description and drawing.

Also it is obvious that depending on numerous factors, such as amount'of combustible material in the catalyst, the composition of the catalyst, the geometrical form and other factors, that numerous modifications in the above procedure may be made without departing from the spirit of the invention.

Also while the foregoing description was in terms of a vertically disposed bed of catalyst with vertical flow of oxygen-containing gas during regeneration, it is obvious that the same procedure could be applied to a horizontal bed.

I cla v i '1. A method of regenerating a contact catalyst body containing combustible materials which comprises igniting the combustible material at catalytic one end of said catalyst body and introducing one end of said catalyst body, forcing oxygen-.

containing gas into the said catalyst body at the end opposite that at which combustion is initiated, the combustion thereafter progressing ina direction opposite that of the flow of the oxygen- .containing gas .and withdrawing the products of combustion from the catalyst body. Y

3. A method of regenerating a heated bed of a contact catalyst bed containing combustible materials which comprises igniting the combustible material at one end of said catalyst bed by introducing a supply of heated oxygen-containing gas into the heated catalyst bed at the said end, discontinuing the supply of said gas and at the opposite end, forcing an oxygen-containing gas, into said bed at an inlet temperature below ignition temperature of said tarry materials, but

' sufficiently high to maintain combustion of said tarry material and efle'cting a continuous flow of oxygencontaining gas through the said bed in a direction which is counter-current to the direction of progress of the combustion.

4. The process as set forth in claim 3 in which the oxygen-containing gas supporting combustion, after the combustible materials are ignited, is introduced into the catalyst at a temperature of about 600 to 700 F. and thereafter is further heated by contact withgthe catalyst.

5. A method of regenerating a body of heated catalyst containing combustible material which comprises passing a heated oxygen-containing gas into contact with the heated catalyst, thus causing active combustion'of the combustible material in a initial zone an thereafter supplying additional oxygen-cont ng gas to support further combustion of combustible material by forcing said gas through the catalyst in a direction opposite that of the direction of progress of the active combustion zone through the catalyst body.

6. The process as set forth in claim 8 in which the catalyst is atcracking temperatures at the moment just prior to ignition of the combustible materials and the oxygen-containing gas introduced into the catalyst bed after the ignition,

is maintained under a back pressure of from about 5 to about 105 pounds per square inch in excess of atmospheric pressure. 

